The present invention relates to an intravenous catheter for medical purposes and, more particularly, concerns an intravenous catheter assembly useful for periodic or intermittent delivery of medication to a patient.
Intravenous catheters through which medication is delivered to a patient are oftentimes expected to be used on more than one occasion for the periodic delivery of the medication to the patient. When using one intravenous catheter, the initial venipuncture and medication delivery are made and then the catheter remains inserted in the patient's vein. Proper closure elements are employed in these type catheters to prevent blood or other body fluids from backflowing out of the catheter which is still in the patient's vein. Thus, instead of making a series of different venipunctures, only one venipuncture is made with this intravenous catheter and follow-up medication is delivered by typically injecting the follow-up medications into the hub of the catheter whereupon it is delivered to the patient. Well known and commonly used reseal plugs in the catheter hub generally provide a technique whereby the injection needle can pierce the plug, deliver the medication and, upon withdrawal of the injection needle, the reseal plug seals itself to prevent backflow of fluids out of the catheter hub. Many of the reseal plugs are made of a thin elastomeric membrane which possesses these desirable reseal properties. However, some problems have arisen when using the reseal plug technique. It has been found that the elastomeric diaphragms loose their resealing characteristics with time. When the catheter may have been on the stock shelf for a considerable period of time, there has been a tendency for the elastomeric material to take a set. When this diaphragm is pierced by the injecting needle and then withdrawn, the slit does not completely close itself whereby leakage may occur. Accordingly, the reliability of elastomeric diaphragms to prevent blood leakage from the catheter is many times in doubt.
A valving device in a blood specimen collection assembly is disclosed in U.S. Pat. No. 3,557,778. The valve in this prior assembly is a ball which is capable of moving to and from an open and closed position to prevent the backflow of testing fluid from a specimen receptacle. There is no disclosure in this prior art patent, however, on the use of such a ball valve in an intravenous catheter which is particularly used for the periodic or intermittent delivery of medication to a patient.
In addition to having an elastomeric sealing diaphragm, many intravenous catheters include a plastic, flexible catheter tube. This type catheter is inserted into the patient in conjunction with an introducer needle which facilitates the venipuncture procedure. After both the introducer needle and introducer catheter tube are positioned in the patient, the introducer needle is carefully withdrawn, leaving the catheter tube to remain in the patient's vein. Use of the plastic catheter tube is beneficial inasmuch as it minimizes trauma to the patient and also reduces risk of injury to the patient if he should suddenly move or roll over on the inserted catheter. Another problem, however, arises when using the plastic, flexible catheter tube.
When medication is to be delivered, the injection needle is usually placed into the hub of the catheter whereupon the fluid is deposited for flow through the catheter tube and on into the patient. However, inserting the injection needle too far into the hub may cause the injection needle to enter the catheter tube and perhaps damage or even puncture the wall of the plastic tube. This damage, of course, may possibly cause particles to enter the bloodstream of the patient, or if the catheter tube has been punctured, some of the medication may not reach the patient. Accordingly, it can be seen that preventative measures are required in this type catheter to prevent the injection needle from damaging or puncturing the catheter tube.
It is to the solution of preventing blood or fluids from flowing out of the catheter hub and of preventing insertion of a sharp instrument into the inside of the catheter tube which the present invention, in its various embodiments, is directed.